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Total Solutions for Tank Fabrication

TIME EQUALS

MONEY

For  

the  

welding  

of  

large  

storage  

tanks,  

a  

partnership  

between  

local  

automation  

specialist  

Mazolutions,  

Lincoln  

Electric  

and  

Chinese-based  

All  

Time  

is  

dramatically  

improving  

the  

quality

and productivity of storage tank construction for the oil and gas sector. African Fusion talks to Andrew Masuret, MD of Mazolutions, about the technology.

Mazolutions’  

partnership  

with  

Lincoln  

Electric  

began  

with  

a  

project  

in  

Secunda  

to  

refurbish  

ashlock  

vessels,  

which  

are  

part  

of  

the  

coal  

gasification  

process.  

“We  

represent  

an  

agency  

out

of  

Germany  

called  

Kistler  

Machines,  

an  

automation  

specialist  

that  

engineers  

and  

supplies  

a  

range  

of  

manipulators  

and  

cutting  

machines.  

With  

Kistler  

as  

our  

manipulation  

partner  

and

Lincoln on the welding side, we were able to develop a highly successful system to do weld overlay cladding on ashlock vessels.

“We  

landed  

an  

order  

in  

2008  

for  

a  

system  

to  

deposit  

an  

erosion  

and  

corrosionImage-9  

protective  

layer  

to  

extend  

the  

life  

of  

the  

ash  

collection  

and  

removal  

system  

on  

these

complex-shaped  

vessels.  

We  

remove  

about  

15  

mm  

of  

existing  

material  

from  

the  

worn  

vessels  

and  

then  

build  

the  

whole  

surface  

back  

up  

to  

OEM  

specifications,”  

Masuret

explains, adding, “this has been an amazingly successful application”

onshore  

and  

offshore  

wind  

tower  

fabrication  

solutions,  

which  

is  

becoming  

increasingly  

interesting  

to  

us  

here  

in  

South  

Africa,”  

he  

adds.  

“Kistler  

wind  

tower  

systems  

offer

significant   

productivity   

advantages,   

because   

they   

are   

fabricated   

using   

multi-wire   

submerged   

arc   

welding   

systems   

and   

two   

circumferential   

seams   

can   

be   

welded

simultaneously,  

so  

eight  

wires  

can  

be  

deposited  

into  

two  

seams  

at  

the  

same  

time,”  

Masuret  

reveals.  

“We  

have  

exceled  

in  

weld  

overlay  

type  

applications,  

and  

we  

are

currently looking at twin-wire hot-wire TIG applications, which are commonly used in the oil and gas industry,” he says.

Moving  

on  

to  

another  

core  

specialism,  

the  

welding  

of  

tank  

seams  

for  

large  

fuel  

and  

gas  

storage  

vessels,  

Masuret  

tells  

of  

his  

partnership  

with  

Chinese  

based  

All  

Time.  

“All

Time  

specialise  

in  

welding  

the  

vertical  

and  

circumferential  

seams  

for  

large  

storage  

tanks  

with  

diameters  

of  

anywhere  

between  

6.0  

m  

and  

100  

m.  

All  

Time  

is  

one  

of  

Lincoln

Electric’s  

biggest  

distributors  

in  

Asia,  

but  

the  

owner,  

Ricky  

Leung,  

realised  

that  

supplying  

product  

was  

not  

enough,  

so  

he  

began  

to  

put  

together  

turnkey  

solutions  

for  

the

tank fabrication business,” Masuret tells African Fusion.

All  

Time’s  

systems  

for  

tank  

farm  

fabrication  

are  

built  

around  

Lincoln  

equipment  

and  

consumables  

for  

two  

welding  

processes;  

submerged-arc  

automatic  

girth  

welding  

(AGW)  

for  

the  

circumferential  

seams  

and

self-shielded electro-gas welding (EGW) for the vertical seams.

Describing  

how  

these  

storage  

tanks  

are  

built,  

Masuret  

says  

that  

there  

are  

two  

basic  

construction  

techniques:  

the  

conventional  

from  

the  

floor  

up  

technique;  

and  

jack

up  

systems  

that  

are  

built  

from  

the  

roof  

down.  

“With  

the  

jack  

up  

system,  

the  

roof  

is  

fabricated  

first,  

then  

the  

whole  

structure  

is  

jacked  

up  

and  

the  

panel  

sections  

are

welded  

in  

underneath.  

All  

Time  

makes  

equipment  

suitable  

for  

both  

techniques.  

Its  

jack  

up  

system  

allows  

a  

tank  

to  

be  

jacked  

up  

to  

accommodate  

the  

next  

section

within  

about  

15  

minutes.  

This  

is  

amazing  

to  

see.  

A  

28  

m  

high  

structure  

with  

a  

100  

m  

diameter  

is  

lifted  

by  

1.5  

to  

3.0  

m  

to  

accommodate  

the  

next  

level,  

all  

using  

a

synchronised set of hydraulic jacks around the periphery,” he relates.

The  

floor-up  

technique  

is  

more  

commonly  

used  

in  

Africa.  

Pre-rolled  

plate  

sections  

with  

accurately  

cut  

weld  

preparations  

are  

lifted,  

one  

by  

one,  

onto  

locating

supports  

and  

tacked  

into  

place.  

The  

vertical  

seams  

between  

each  

plate  

section  

are  

then  

completed.  

“Traditionally,  

SMA  

(stick)  

welding  

was  

used  

to  

complete  

these

joints,  

and  

it  

would  

take  

a  

manual  

welder  

about  

two  

days  

to  

fill  

a  

single  

2,4  

m  

joint.  

We  

experimented  

with  

various  

types  

of  

equipment,  

for  

a  

period  

of  

time,  

trying

to  

find  

a  

solution  

for  

the  

vertical  

joints.  

But  

modern  

All  

Time  

systems  

use  

the  

EGW  

process,  

which  

is  

almost  

like  

a  

casting  

process  

that  

enables  

these  

vertical  

seams

to be filled in a single pass,” Masuret reveals.

At  

the  

start  

of  

the  

EGW  

process,  

a  

water-cooled  

copper  

backing  

bar  

is  

inserted  

behind  

the  

V-prepped  

weld  

joint  

and  

wedged  

into  

tight  

contact  

along  

the  

seam.  

A  

welding

head  

surrounded  

by  

a  

copper  

shoe  

is  

mounted  

in  

a  

carriage  

in  

front  

of  

the  

joint.  

Typically  

using  

a  

Lincoln  

DC  

600  

welding  

power  

source  

and  

a  

2,4  

mm  

Lincoln  

Electric

self-shielded NR431welding wire, an arc is struck and molten metal from the wire is poured into the gap between the two copper backing bars.

“The  

travel  

speed  

of  

the  

welding  

head  

and  

floating  

copper  

shoe  

is  

governed  

by  

the  

stick-out  

of  

the  

consumable  

wire,  

which  

melts  

into  

the  

weld  

puddle.  

The  

result  

is  

that

the  

shoe  

travels  

up  

at  

same  

speed  

as  

the  

joint  

is  

being  

filled,”  

explains  

Masuret.  

“With  

this  

process,  

excluding  

the  

tie-ins,  

a  

2,4  

m  

vertical  

seam  

can  

be  

completed  

in

around  

20  

minutes  

at  

deposition  

rates  

of  

up  

to  

27  

kg/h,”  

he  

says,  

adding  

that  

welding  

is  

generally  

done  

from  

the  

inside  

of  

the  

tank  

with  

the  

entire  

welding  

system

hanging off the top of the plate section. The welder stands on a floating table inside the unit and raises himself upwards as welding progresses.

“On  

a  

site  

in  

Durban,  

a  

welder  

and  

one  

helper  

were  

able  

to  

complete  

11  

vertical  

seams  

per  

day  

using  

this  

system,  

while  

previously,  

it  

took  

two  

days  

for  

a  

single  

vertical

seam. That amounts to a 22-fold improvement in productivity,” he calculates.

calculates.  

Once  

two  

rings  

of  

plate  

sections  

are  

installed  

and  

the  

vertical  

seams  

completed,  

the  

process  

to  

complete  

a  

circumferential  

seam  

begins.  

The  

basic  

process  

is

the  

same  

for  

both  

floor-up  

and  

roof  

down  

designs.  

An  

AGW  

unit  

is  

first  

suspended  

from  

the  

top  

edge  

of  

the  

shell,  

usually  

from  

the  

inside  

of  

the  

tank  

being  

constructed.

Straddling the shell plates, the system rides on adjustable flange wheels and travels at a controllable speed around the girth seam of the tank.

The  

seam  

is  

filled  

using  

the  

single  

or  

twin-arc  

SAW  

process.  

“All  

Time  

recommends  

using  

tried  

and  

tested  

Lincoln  

SAW  

equipment  

and  

consumables,  

and  

Lincoln’s

submerged arc power sources,” says Masuret, adding that all welding is completed to the API 650 welding code. Key feature of the AGW system include:

A laser pointer on the weld head for easy wire tip positioning.

A handrail, operator seat, and weatherproof curtain around the unit.

An integrated CE-marked Lincoln NA3 master control panel for sequence control and easy operation.

Enclosed dual motors with ac inverter drives for steady and consistent travel speeds along the tank shell diameter.

A Lincoln NA3 SAW weld head with an ergonomically arranged flux delivery and containment belt.

A powerful blower type vacuum belt for flux recycling.

A standard electric flux winch to lift the flux hopper off the ground and position it

“We  

are  

currently  

delivering  

a  

system  

to  

a  

client  

in  

Mozambique,  

so  

we  

have  

set  

up  

a  

facility  

here  

in  

Heidelberg,  

first  

to  

give  

our  

client  

the  

opportunity  

to  

see  

the  

equipment  

in  

action  

before  

buying  

it,  

but

we also use it to train welders on how to best use the system,” Masuret informs

Are  

there  

many  

tank  

projects  

in  

the  

pipeline?  

“As  

well  

as  

the  

ongoing  

work  

in  

Durban;  

Richards  

Bay,  

Cape  

Town  

and  

Saldanha  

are  

all  

looking  

to  

expand  

–  

and  

LNG  

is  

going  

to

be a massive opportunity in South and Southern Africa,” he responds.

On  

the  

quality  

of  

the  

end  

result,  

he  

cites  

a  

client,  

MM&G  

from  

Boksburg,  

involved  

in  

constructing  

tanks  

for  

one  

of  

the  

new  

power  

stations.  

According  

to  

company  

MD,  

Dawie

Vos,  

who  

has  

been  

using  

AGW  

and  

EGW  

systems  

from  

All  

Time  

since  

April  

2014,  

the  

pass  

rate  

on  

X-rays  

has,  

to  

date,  

been  

at  

99%,  

a  

huge  

improvement  

on  

manual  

SMAW

welding,  

which  

is  

plagued  

by  

stop/start  

weld  

flaws.  

“Proper  

use  

of  

this  

equipment  

allows  

these  

tanks  

to  

be  

fabricated  

far  

faster,  

with  

higher  

quality  

and  

lower  

repair  

rates  

than

possible by the best stick welders,” Masuret assures, “which leads to lower risks and lower project costs,” he adds

“We  

adopt  

very  

strong  

partnerships  

with  

reputable  

and  

experienced  

suppliers.  

By  

combining  

our  

local  

knowledge  

and  

automation  

expertise;  

Lincoln  

Electric’s  

welding

experience,  

equipment  

and  

consumables;  

and  

the  

global  

technical  

knowledge  

of  

partners  

such  

as  

All  

Time  

and  

Kistler,  

we  

are  

able  

to  

provide  

full  

turnkey  

solutions,  

from  

the

conceptualisation of a project all the way through to the commissioning of a construction,” Masuret concludes.

> NEWS by African Fusion | Sep 17, 2015
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